BosConfig - Defines server processes for the BOS Server to monitor
The BosConfig file lists the processes that the Basic OverSeer (BOS) Server monitors on its server machine, and thus defines which AFS server processes run on the machine. It specifies how the BOS Server reacts when a process fails, and also defines the times at which the BOS Server automatically restarts processes as part of performance maintenance. The file must reside in the /etc/yfs/server directory on each AFS server machine.
A server process entry in the BosConfig file records the following information:
The entry type, which is one of the following:
Designates a server process that runs periodically instead of continuously.
The BOS Server starts a cron process only at specified times,
not whenever it fails.
All standard AFS process entries except dafs are simple (there are no standard cron processes).
Designates a group of interdependent server processes. If one of the processes fails, the BOS Server must coordinate its restart with the restart of the other processes in the group, possibly by stopping them first.
There is only one standard entry of this type,
for which the conventional name is dafs.
It combines four server processes: the File Server (fileserver process),
the Volume Server (volserver process),
the Salvager (salvager process),
and the Salvager Server (salvageserver process.
These processes all operate on the same data--the AFS data stored on an AFS server machine's /vicep partitions and mounted in the AFS filespace--but in different ways.
Grouping the processes prevents them from attempting to access the same data simultaneously,
which can cause corruption.
During normal operation, the Salvager process is not active. If the File Server process fails, however, the BOS Server stops the Volume Server process and runs the Salvager process to correct any corruption that resulted from the failure. (The administrator can also issue the bos salvage command to invoke the Salvager process.) If the Volume Server fails, the BOS Server can restart it without stopping the File Server or running the Salvager.
Designates a server process that runs independently of any other on the server machine. If a simple process fails, the BOS Server does not have to coordinate its restart with any other process.
The entry name. The conventional name for an entry in the BosConfig file and the associated process matches the binary filename. When issuing any bos command that takes the -instance argument, identify each process by the name used in the BosConfig file. For a list of the names, see the bos create reference page.
The process's status flag,
which determines whether the BOS Server attempts to start the process in two cases: each time the BOS Server itself restarts,
and when the process fails.
The BosConfig file currently uses a binary notation to indicate whether the BOS Server attempts to restart the process as necessary or does not monitor it at all.
For the sake of clarity,
the AFS documentation refers to the flags as Run and NotRun instead.
Only a system administrator,
not the BOS Server,
can change the flag.
One or more command parameters which the BOS Server invokes to start the process or processes associated with the entry:
A cron entry has two command parameters,
the first the complete pathname to the program,
and the second the time at which the BOS Server invokes the program.
The dafs entry has three command parameters,
each the complete pathname to the fileserver,
volserver,
salvager and salvageserver programs,
in that order.
A simple entry has only one command parameter,
the complete pathname to the program.
In addition to server process entries, the BosConfig file specifies the times at which the BOS Server performs two types of automatic process restarts:
The general restart time at which the BOS Server restarts itself and then each process for which the entry in the BosConfig file has status flag Run.
The default setting is Sunday at 4:00 a.m.
The binary restart time at which the BOS Server restarts any server process for which the time stamp on the binary file in the /usr/local/libexec/yfs directory is later than the last restart time for the process. The default is 5:00 a.m.
Finally, there is an entry specifying whether the BOS Server will start in restricted mode.
Although the BosConfig file is in ASCII format, it is normally best not to use a text editor to alter it. The parser is very picky, and incorrectly formatted entries can prevent server startup in ways that are difficult to diagnose. Instead, use the appropriate commands from the bos command suite:
The bos create command to create an entry in the file and start the associated process.
The bos delete command to remove an entry from the file after the bos stop command is used to stop the associated process.
The bos getrestart command to display the times at which the BOS Server performs automatic restarts.
The bos getrestricted command to display whether the BOS Server is running in restricted mode.
The bos setrestart command to set the times at which the BOS Server performs automatic process restarts.
The bos setrestricted command to place the BOS Server in restricted mode.
The bos start command to change an entry's status flag to Run and start the associated process.
The bos status command to display all processes listed in the file.
The bos stop command to change an entry's status flag to NotRun and stop the associated process.
There are also bos commands that start and stop processes without changing entries in the BosConfig file. The BOS Server reads the BosConfig file only when it starts, transferring the information into its memory. Thus a process's status as represented in the BOS Server's memory can diverge from its status in the BosConfig file. The following commands change a process's status in the BOS Server's memory only:
The bos restart command restarts a specified set of processes, all processes, or all processes other than the BOS Server.
The bos shutdown command stops a process.
The bos startup command starts a process.
When the BOS Server shuts down, it rewrites BosConfig, discarding any changes made manually to that file. To change the configuration for the next BOS Server restart, instead write a new file to BosConfig.new. If BosConfig.new exists when the BOS Server starts, it will rename that file to BosConfig before reading its configuration.
bos_create(8), bos_delete(8), bos_getrestart(8), bos_getrestricted(8), bos_restart(8), bos_setrestart(8), bos_setrestricted(8), bos_shutdown(8), bos_start(8), bos_startup(8), bos_status(8), bos_stop(8), bos_salvage(8), fileserver(8), salvager(8), volserver(8)
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